Demonstrate your knowledge by indicating which of the following
is a key.

a)

CE

b)

BDE

c)

ABCDE

d)

AD

4.

Let R(ABCDE) be a relation in Boyce-Codd Normal
Form (BCNF). If ABC is the only key for R, describe all the
nontrivial functional dependencies that hold for R. Identify one of
these FD's from the following list.